The present invention relates to a fluid dispenser, and more particularly to a pen style correction fluid dispenser for application of a correction fluid to a print medium to make small to medium size corrections of, for example, typed and pen written documents.
With the increased use of correction fluids in preparing typed or pen written documents for example, various applicators and dispensers may be found in the marketplace, all of which have met with success, from the brush type to the more recent pen type applicators. Generally, the correction fluids used in these devices employ a halogenated hydrocarbon as a solvent. In the pen type or enclosed correction fluid dispensers, these solvents have a vapor phase which is present in the head space of the dispenser and these vapors exert a pressure equal to the vapor pressure of the solvent. The pressure in the head space is also effected by the ambient temperature, and as the temperature increases, the pressure in a fixed volume is directly proportional to the temperature increase.
Additionally, the specific gravity of the correction fluid is inversely effected by the temperature and as the temperature increases, the specific gravity decreases. Therefore, as the temperature increases, the volume occupied by the fluid increases and the head space decreases, causing pressure in the head space to increase. Therefore, when a valve or other release device is open to make a correction, and the head space pressure exceeds the ambient pressure, correction fluid can be driven out of the dispensing valve in volumes large enough to cause an unacceptable correction.
It is therefore an object of the present invention to provide a pen type correction fluid dispenser which is less effected by the differences in ambient and internal pressures than those dispensers of the prior art.
A further object of the invention is to provide a correction fluid dispenser of the type described above which provides the user control of the amount of fluid dispensed with a minimum of effort and with reliability.
Still another object of the invention is to provide a correction fluid dispenser of the pen type which is simple to manufacture and which contains a minimum number of parts.